This invention relates generally to electronic devices, and more particularly, to electronic devices including capacitor circuitry.
Electronic devices such as handheld electronic devices and other portable electronic devices are becoming increasingly popular. Examples of handheld devices include cellular telephones, handheld computers, media players, and hybrid devices that include the functionality of multiple devices of this type. Popular portable electronic devices that are somewhat larger than traditional handheld electronic devices include laptop computers and tablet computers.
Due in part to their mobile nature, portable electronic devices are often provided with wireless communications capabilities. For example, portable electronic devices may use long-range wireless communications to communicate with wireless base stations and may use short-range wireless communications links such as links for supporting the Wi-Fi® (IEEE 802.11) bands at 2.4 GHz and 5 GHz and the Bluetooth® band at 2.4 GHz.
Wireless communications circuitry often includes discrete components such as discrete capacitor components. Such discrete components are typically packaged and mounted to a printed circuit board. However, packaged components include parasitics that contribute to non-ideal functionality. For example, a packaged capacitor component includes parasitic inductance associated with package terminations such as leads or conductive termination caps. In this scenario, the combination of capacitance and inductance produces a self-resonant frequency above which the packaged capacitor component appears inductive. Such self-resonant characteristics can be useful for single-band applications where the capacitor has a low-impedance at the self-resonant frequency. However, for dual or multiple band applications, such self-resonant characteristics are undesirable. Consider the scenario in which a radio-frequency path is used for communications on both 2.4 GHz and 5 GHz. In this scenario, a single capacitor component in the radio-frequency path that serves as a direct-current (DC) blocking capacitor can only have one self-resonant frequency which must be chosen either to provide a low-impedance in the 2.4 GHz band, or a low-impedance in the 5 GHz band, or somewhere in between the two. Thus, the value of a single DC blocking capacitor chosen for dual-band 2.4 GHz and 5 GHz applications must necessarily be a compromise between the two bands of operation and the RF signal loss (due to the impedance of the capacitor in series with the transmission line) ends up being non-optimal for either band.
It would therefore be desirable to be able to provide packaged capacitor components with improved self-resonance characteristics.